On many occasions it would be very handy to calculate the values of custom field sets and store that calculated value within Civi.

I'll use a survey for example.

I'd like to create a scored survey activity type tied to a custom field set. The field set would include multiple fields, each with select options. The final field within the set would be "Score." I'd like this field to add the values of all answers. Once we calculate the survey score we can do all kinds of fancy stuff.

I've done my due diligence but didn't find anything out there.

If there isn't one, is the extension route the most efficient method?

Ideally, I'd love to have "Calculated Field" be an option for data type when creating custom fields but that may be a pipe dream.